OAK

[coach]

Any pointers for cutting 1 7/8" oak?
The parts are 24" x 18". I have a prs alpha with 2 fein vacs for hold down.
Any suggestions will be helpful before I start cutting.
Thanks, David

[Gary Campbell]

David...
The acids in Oak like to gum up the bit. We have destroyed bits by cutting too conservatively. Lower your RPM and increase move speeds (even if you have to sacrifice pass depth) to keep the bit cool. I had good luck with an Onsrud .5 downspiral, .5 pass depth, 2+ ips. 10K rpm (increase move speed till good chips fly)
Gary

[ljdm]

Most of what I cut is white oak, average speed of 2.5ips, rpm 16k (PC router). Both up and down spirals, usually 1/4"bit, .2 per pass. Will run a cleanup pass if needed for cut quality, 1/4" bit flexes more than a 1/2" bit. Using 2 feins for holddown. Those numbers are with a PR/PRT, you could probably be more agressive with the Alpha.

Gary - you cut oak at 10k - spindle, I assume?

[beacon14]

I would do this in 1/4" deep passes, 1/2" downcut spiral (upcut will clear chips better but more likely to lose your vacuum), 14K RPM at 3-4 IPS.

The most important advice I can give you (other than to use a nice sharp bit) is to create a toolpath that is wider than the bit, i.e. for each pass depth you want two passes, one with a fairly large allowance (something like 1/2 the bit diameter) and one with no allowance. That creates a 3/4" wide trough for the 1/2" bit to travel in, so the bit is not rubbing the walls of the cut on both sides as it gets deeper into the material. For each pass depth make the allowance cut first then the finish cut.

The allowance cut can be climb or conventional but the finish cut should be a climb cut.

[Gary Campbell]

Lou...

Yes. Did that in an attempt to keep chipload up with slow move speed required for this job. We were cutting .5" deep slots.
Gary